If you'd told me two months ago that the most consistent personal trainer, nutritionist and accountability partner in my life would be a chatbot, I’d have smiled politely and moved on. I’ve worked in advertising long enough to spot a gimmick. Or so I thought.

What actually happened surprised me. It wasn’t just that ChatGPT helped me transform my health. It’s that it did it better than any system, tracker, coach or app I’ve used before. And more importantly, it did it in a way that actually stuck.

The shift

The real shift, for me, was moving from “trying to be good” to knowing what good actually looks like. I had to relearn what nutrition actually is. Not the filtered Instagram kind, not the low-carb spreadsheet kind either. Just the honest stuff: whole foods, protein, carbs when you need them, and not overcomplicating it.

That’s where ChatGPT became genuinely useful. Every day, I’d track what I’d eaten. Two flat whites, a bowl of oats, half a bag of nuts, a few rice cakes. I’d check in and ask, did I do OK today? Without judgement, it would break down the calories, the protein, the fat, the energy balance. It reminded me of the principles I already knew but had forgotten in the fog of modern life.

This wasn't calorie-counting in the obsessive, MyFitnessPal kind of way. It was conversational. Encouraging. And constant. Like having a PT in your pocket who never rolled their eyes or told you to "just push through."

Three small surprises

1. It kept me honest, kindly. I didn't have to log into anything. I just typed what I’d eaten. Or how I felt. And it tracked the patterns. When I was under-eating. When I was tired. When I was lying to myself about “just a few crisps.”

2. It gave me confidence to train intuitively. No over-engineered programme, just steady encouragement to lift heavy, track effort, and recover well. Even when I only had 30 minutes. It remembered what I’d done last time, suggested where to pick up. And when I was overtraining, it told me to rest.

3. It wasn’t preachy. The tone mattered. If it had sounded like a TED Talk on discipline or another hustle-culture “win the day” mantra, I’d have ignored it. But it just asked good questions and answered mine better.

Practical tips for using ChatGPT as your PT:

1. Create a dedicated thread and name it. Mine is called Bulk to Trim Guide. This gives it context and continuity.

2. Start by sharing your objectives. Be clear. Lose weight? Gain muscle? Train smarter? Set that tone early.

3. Keep it conversational. Treat it like a sounding board. Ask questions, report meals, share doubts. It becomes more valuable when you talk to it like a human.

4. Use it mid-workout. Tell it what you’ve done and get advice on what to do next. Especially useful when the gym is busy or your plan’s thrown off.

5. Short on time? Send it a photo of your plate. I do this often. It breaks down calories, macros and gives feedback on what’s missing, instantly.

6. Use it in everyday life. My wife’s 30 weeks pregnant and wanted a better cereal for the third trimester. I sent a photo of the cereal aisle. ChatGPT picked two pregnancy-safe, fibre-rich, actually tasty options I knew she’d like.

Screenshot from ChatGPT giving me a breakdown of my meal, taking me just second to record my food on the fly.

The human bit

Of course, the commitment still had to come from me. I changed what I ate. I trained consistently. I walked hills. I made it a lifestyle. But having a reliable sounding board, one that remembered everything and never lost patience, helped more than I expected.

I’ve now lost 8kg in just under a month. I’m sleeping better. My shirts fit looser. My energy is up. Most of all, I’ve stopped second-guessing myself. I know what good looks like now, and it’s surprisingly simple.

If you’re curious about where to start, begin by reminding yourself what real food looks like. One tool that helped me reset the basics was Armz Korleone’s all-natural nutrition guide. Armz is a friend, a former Musclemania UK Champion, and someone I now support as a digital creator. Training around people like him has shown me that the right people don’t just motivate you. They give you momentum.

And if you’re interested in what AI can do beyond brand guidelines and deck writing, try pointing it at something personal. You might find it gives you back more than it takes.

About the author
Steve Sharpe is a London-based senior client lead working in marketing and digital content. He has helped deliver campaigns and grow revenues for blue chip brands including Microsoft, Stellantis and the John Lewis Partnership, and has worked on marketing projects involving Ed Sheeran and online fitness creator Armz Korleone. Alongside his professional work, he is passionate about fitness, boxing, animal welfare and the everyday joy of becoming a father.